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Connect two i2c sensors in OpenPlotter 1.2.0
#1
Hello there,

I have an issue with two i2c sensors: an MPU9255 and a BME280. Both of them are connected in parallel to a raspberry 3b+ with OpenPlotter 1.2.0a. However only data from the BME280 is received when both sensor are connected. If I disconnect the BME280 I can then receive data from the MPU.
So both sensors independently work fine and run on two different addresses, 0x76 and 0x68. In the i2c tab they are both shown, and when the BME280 is unplugged I can calibrate my MPU on the pypilot tab. But I can't receive data from both of them at the same time...
I don't see what the problem can be, some help would help :-)
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#2
By 1.2.0a you mean 1.2.0 alpha ?
Are both sensors recognized in OP's I2C tab ?
Cordialement
Didier B
Pi4, SSD USB3, OP 3.0 Touch SK 3.2.1 OpenCPN  5.8.4 :  Thank you  Thank you  Thank you


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#3
(2019-05-19, 05:51 AM)Didier B Wrote: By 1.2.0a you mean 1.2.0 alpha ?
Are both sensors recognized in OP's I2C tab ?

Hi Didier,

Yes, I meant 1.2.0 alpha.

And yes both are recognised in the OP I2C tab.
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#4
I am thinking, could it be due to loss of signal over cable length? I am using grounded signal cable running over 4 meters for both sensors.

I know I could test the sensors close to the Raspberry but then I will have to dismantle my installation and it will take quite a bit of time...

Anyone has another idea of what the problem could be?
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#5
i would keep the mpu close to the pi under a meter and away from magnets and metal
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#6
(2019-05-19, 07:34 AM)Barentsailor Wrote:
(2019-05-19, 05:51 AM)Didier B Wrote: By 1.2.0a you mean 1.2.0 alpha ?
Are both sensors recognized in OP's I2C tab ?

Hi Didier,

Yes, I meant 1.2.0 alpha.

And yes both are recognised in the OP I2C tab.
the aanswer is yes to both questions
Cordialement
Didier B
Pi4, SSD USB3, OP 3.0 Touch SK 3.2.1 OpenCPN  5.8.4 :  Thank you  Thank you  Thank you


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#7
So I ended up replacing my cables for CAT6 ethernet cables and it works very good. Now both of my I2C sensors work perfectly together.

I had some standard 4 stranded shielded signal cable. Apparently not good enough to convey I2C signal for two sensors over more than 4 meters...
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#8
Gentelmen

I am using BME 280 on the 1,00 version, I gets recognized, but I cannot see the correct values on OpenCpn. I think it's not translated correctly to NMEA 0183 sentences. Temperature appears as -271 degrees. Could you tell me what NMEA sentences you used to make it work?

Thanks a lot!

Paulo
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#9
a few things to check.
setup in i2c tab "environmental outside temp"
tools / nmea 0183 generator / opencpn defaults
wiring.
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#10
(2019-06-13, 12:41 AM)jim321 Wrote: a few things to check.
setup in i2c tab "environmental outside temp"
tools / nmea 0183 generator / opencpn defaults
wiring.

Thanks a lot Jim
Wiring seems to be ok. BME 208 seems to be recognized. Please see the image with the I2C tab, NMEA generator , signal K diagnostic and Open CPN. Pressure and pressure history are 0 and temperature is 273,1!

What should be wrong here?

Thanks in advance!

Paulo
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